The objective of this research is the elucidation of roles of various pathophysiologic processes in the occurrence of experimental cerebral edema. This includes quantification and correlation of the crucial variables of regional cerebral blood flow, regional cerebrovascular reactivity and regional energy metabolism as well as regional assays of brain tissue levels of norepinephrine, dopamine, 5- hydroxytryptamine and GABA, in areas rendered edematous by cold injury as well as adjacent and more remote areas. The therapeutic modalities of corticosteroids, hyperosmolar agents and prolonged hyperventilation are being studied.